Displacement reactions are phase transitions wherein two or more elements or compounds in the solid phase react to form new product compounds that are more thermodynamically stable than the starting reactants. The formation of the stable product phases is accompanied by specific morphologies that can give the resultant composite desirable properties. Displacement reactions have been used for making composite materials as described in SYNTHESIS OF A MoSi.sub.2 --SiC COMPOSITE IN SITU USING A SOLID STATE DISPLACEMENT REACTION, C H Henager, J L Brimhall, J P Hirth, Mat. Sci. and Engr. A155 (1992) 109-114, and for making a film product as discussed in U.S. Pat. No. 5,462,902, as well as in SYNTHESIS OF Ti.sub.3 SiC.sub.2 /SiC AND TiSi.sub.2 /SiC COMPOSITES USING DISPLACEMENT REACTIONS IN THE Ti--Si--C SYSTEM, R. Radhakrishnan, C H Henager, Jr., J L Brimhall, S B Bhaduri, Scripta Metallurgica, Vol. 34, No. 12, pp. 1809-1814, 1996. However, displacement reactions have not been suggested for any other uses.
Joining of ceramics has been a problem for centuries. Metals can be welded and fastened together, but ceramics cannot be welded and the low fracture toughness of ceramics makes mechanical fastening difficult. The large differences in thermal expansion between metals and ceramics makes dissimilar materials joining a difficult problem, also. Presently, products using ceramics or that require ceramic/metal connections are generally designed to minimize the need to join ceramics. Accordingly, there is a need for a method to join ceramic parts and to join ceramics to metals.